Synergistic effect of straw-mulch and mycorrhiza-biofertilizer in increasing yield of black rice intercropped with soybean on raised-beds in aerobic irrigation system

Application of mycorrhiza-biofertilizer and intercropping with legume crops could improve performance and yield of red-rice grown onraised-beds under aerobic irrigation systems, but weeds became a serious problem, which needs more frequent weeding. A Split Split-Plot (SSP) experiment was designed to examine synergistic effects of rice-straw mulch and mycorrhiza-biofertilizer application on yieldof several black rice promising-lines that were additively intercropped with soybean on aerobically irrigated raised-beds. Three treatmentfactors including black-rice genotypes (G3, G9, G4/15), straw mulching (S0= without; S1= with mulch), and mycorrhiza-biofertilizer(M0= without; M1= with biofertilizer) were arranged as the main, subplots and sub-subplots respectively in three blocks (replications).The results indicated that straw mulch and biofertilizer application significantly increased growth and yield of the black rice plants, whilethe genotypes were also significantly different in several growth and yield variables. However, there were significant interaction effectsof mycorrhiza-genotypes (M*G), mycorrhiza-straw (M*S), and mycorrhiza-straw-genotype (M*S*G) on several growth and yield variables,indicating variation of responses to mycorrhiza among the genotypes. The M*S*G interaction also indicated synergistic effects betweenstraw mulch and mycorrhiza biofertilizer in increasing the black rice yield, in which the S1M1 treatment resulted in the highest grain yieldon the G4/15 line (58.2 g/clump) while the S0M0 treated G9 line showed the lowest yield (29.8 g/clump).